A niobium-tin superconducting wire and its assembly structure

Abstract

The present invention belongs to the technical field of superconducting wires, and relates to a niobium-tin superconducting wire and its assembly structure. The present invention provides an assembly structure of a niobium-tin superconducting wire, the assembly structure comprising: a plurality of hexagonal subcomponents, a plurality of fan-shaped subcomponents, and a Ta tube drilled with a plurality of hexagonal holes; the hexagonal subcomponents are inserted into the Ta tube drilled with a plurality of hexagonal holes, and the Ta tube is surrounded by an annular subcomponent composed of a plurality of fan-shaped subcomponents, and the outer ring of the annular subcomponent is sequentially coated by a barrier layer and an oxygen-free copper tube. The assembly structure provided by the present invention is, firstly, conducive to uniform deformation of the core wire within the subcomponent and isolation of the core wire between the subcomponents, thereby reducing the loss of the Nb3Sn superconducting wire; secondly, it enables the Sn inside each subcomponent to fully react with Nb, ensuring the full generation of the Nb3Sn superconducting phase and improving the critical current density of the Nb3Sn superconducting wire.

Description

Technical Field

[0001] The invention belongs to the technical field of superconducting wires and relates to a niobium-tin superconducting wire and an assembly structure thereof. Background Art

[0002] Niobium tin superconducting wire (Nb3Sn superconducting wire) is widely used in large scientific facilities such as particle accelerators and nuclear fusion experimental reactors due to its high critical current density. It is also used in medical imaging equipment such as nuclear magnetic resonance imaging devices and has a wide range of applications and developments in the field of superconducting materials. Among them, the internal tin method is an important technology for preparing Nb3Sn superconducting wire and is currently the first choice for preparing low-cost and high-current density Nb3Sn superconducting wire.

[0003] When preparing Nb3Sn superconducting wire by the internal tin method, Nb rods are usually inserted into the porous copper ingots obtained by the drilling method, and CuNb composite rods are obtained after extrusion. Then, the Sn core rod is inserted into the CuNb composite tube after the central drilling, and the subcomponents are obtained by multiple drawing passes. Finally, the barrier layer and the subcomponents are assembled into an oxygen-free copper tube, and the finished superconducting wire is obtained by multiple drawing passes. Finally, the Nb3Sn phase is generated by heat treatment reaction. However, the Nb3Sn superconducting wire prepared by this method is prone to serious core wire overlap due to the uneven deformation of the subcomponents during the drawing process, resulting in high wire loss. At the same time, in the final heat treatment reaction, the Sn in each subcomponent may diffuse into the adjacent subcomponent, resulting in the possibility that the lack of Sn inside the subcomponent makes the reaction between Nb and Sn insufficient, which makes the wire unable to reach the pre-designed critical current density level. Summary of the invention

[0004] The purpose of the present invention is to solve the technical problems that the assembly structure of Nb3Sn superconducting wire prepared by the internal tin method is prone to uneven deformation of subcomponents, diffusion of Sn to adjacent subcomponents and insufficient reaction. In this regard, the present invention provides a niobium-tin superconducting wire and its assembly structure to solve this need in the art.

[0005] In one aspect, the present invention relates to an assembly structure of a niobium-tin superconducting wire, the assembly structure comprising: a plurality of hexagonal subcomponents, a plurality of fan-shaped subcomponents, and a Ta tube drilled with a plurality of hexagonal holes;

[0006] The hexagonal subcomponent is inserted into the Ta tube drilled with a plurality of hexagonal holes, and the Ta tube is surrounded by an annular subcomponent composed of a plurality of the fan-shaped subcomponents, and the outer ring of the annular subcomponent is covered by a barrier layer and a stabilizing matrix in sequence.

[0007] Furthermore, in the assembly structure of the niobium-tin superconducting wire provided by the present invention, the hexagonal subcomponent or the fan-shaped subcomponent is a CuNb composite tube with a Sn2Ti alloy rod inserted in the center.

[0008] Furthermore, in the assembly structure of the niobium-tin superconducting wire provided by the present invention, in the hexagonal subcomponent or the fan-shaped subcomponent, the mass ratio of Nb to Sn is 1.5-4.0.

[0009] Furthermore, in the assembly structure of the niobium-tin superconducting wire provided by the present invention, the hexagonal holes in the Ta tube drilled with a plurality of hexagonal holes are separated from each other by Ta and are not connected.

[0010] Furthermore, in the assembly structure of the niobium-tin superconducting wire provided by the present invention, the adjacent spacing between the hexagonal holes is 5-15 mm.

[0011] Furthermore, in the assembly structure of the niobium-tin superconducting wire provided by the present invention, the diameter of the Ta tube drilled with a plurality of hexagonal holes is Φ20-45 mm, and the cross-sectional dimensions of the hexagonal holes are H5-H15 mm.

[0012] Furthermore, in the assembly structure of the niobium-tin superconducting wire provided by the present invention, the material of the barrier layer is Ta.

[0013] Furthermore, in the assembly structure of the niobium-tin superconducting wire provided by the present invention, the material of the stable matrix is ​​oxygen-free copper.

[0014] On the other hand, the present invention relates to a niobium-tin superconducting wire, which is obtained by subjecting the assembly structure of the niobium-tin superconducting wire to multiple stretching forming and heat treatment.

[0015] Furthermore, in the niobium-tin superconducting wire provided by the present invention, the stretching speed of the multi-pass stretching is 5-50 m / min, and the processing rate of each pass is 5%-30%.

[0016] Compared with the prior art, the technical solution provided by the present invention has at least the following beneficial effects or advantages:

[0017] The present invention optimizes the assembly structure of the existing internal tin method for preparing Nb3Sn superconducting wires, and separates the hexagonal subcomponents from each other by inserting a drilled Ta tube. First, the introduction of Ta constraints around the subcomponents is conducive to uniform deformation of the subcomponents during the stretching process, avoiding the increase of hysteresis loss caused by uneven deformation of the core wire in the subcomponents; second, it avoids the coupling loss caused by the core wire between each hexagonal subcomponent and between the hexagonal subcomponent and the annular subcomponent, thereby reducing the loss; third, by separating each hexagonal subcomponent with Ta, and separating the hexagonal subcomponent and the annular subcomponent with Ta, it is avoided that the Sn in the subcomponent diffuses to the outside, so that the Sn inside each subcomponent can fully react with Nb, ensuring the full generation of the Nb3Sn superconducting phase, and improving the critical current density of the Nb3Sn superconducting wire. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 This is a schematic diagram of the cross-sectional structure of the assembly structure of the niobium-tin superconducting wire provided by the present invention.

[0020] Explanation of the accompanying drawings: 1. stable matrix; 2. barrier layer; 3. fan-shaped subcomponent; 4. drilled Ta tube; 5. hexagonal subcomponent. DETAILED DESCRIPTION

[0021] The technical scheme of the present invention is described below in conjunction with the embodiments, but the present invention is not limited to the following embodiments. The experimental methods and detection methods described in each embodiment are conventional methods unless otherwise specified; the reagents and materials can be purchased on the market unless otherwise specified. The % in the following embodiments, unless otherwise specified, are all mass percentages. The ratios in the following embodiments, unless otherwise specified, are all mass ratios.

[0022] The present invention provides a method for preparing a niobium-tin superconducting wire by an internal tin method, comprising the following steps:

[0023] Step 1, after drilling a hole in the center of the multi-core CuNb composite rod, insert the Sn2Ti alloy rod, and prepare the hexagonal subcomponent 5 and the fan-shaped subcomponent 3 through multiple stretching, with the Nb / Sn mass ratio being 1.5-4.0.

[0024] Step 2, select a Ta rod with a diameter of Φ20~45mm, and use a deep hole drilling method to drill a number of hexagonal through holes along the length direction of the Ta rod. The cross-sectional dimensions of the hexagonal through holes are H5~H15mm, and a drilled Ta tube 4 is obtained.

[0025] Step 3, the hexagonal sub-components 5 are loaded into the through holes of the drilled Ta tube 4, so that the hexagonal sub-components 5 are separated from each other by Ta. The fan-shaped sub-components 3 are uniformly surrounded on the outer ring of the drilled Ta tube 4 to form an annular sub-component, the fan-shaped sub-components 3 in the annular sub-component are connected to each other, the fan-shaped sub-components 3 and the hexagonal sub-components 5 are separated from each other by Ta, the barrier layer 2 is uniformly coated on the outer ring of the annular sub-component, and then loaded into the stable matrix 1 to obtain the final blank.

[0026] Step 4, the final billet is subjected to multiple stretching forming and heat treatment to obtain Nb3Sn superconducting wire, the stretching speed is 5~50m / min, the processing rate of each pass is 5%~30%, and the heat treatment method is first keeping warm at 575℃ for 100h and then keeping warm at 650℃ for 100h.

[0027] Example 1

[0028] This embodiment provides a process for preparing a Nb3Sn superconducting wire.

[0029] In this embodiment, the material of the barrier layer 2 is Ta, and the material of the stabilizing substrate 1 is oxygen-free copper.

[0030] The center of a 200-core CuNb composite rod with a diameter of Φ55mm was deep-drilled to a diameter of Φ20mm, and the cleaned Sn2Ti alloy rod was inserted into the central drilled hole of the CuNb composite tube to obtain a subcomponent blank. The subcomponent blank was subjected to multi-pass stretching and cut-to-length to obtain a hexagonal subcomponent 5 and a fan-shaped subcomponent 3, with an Nb / Sn ratio of 2.0. The processing rate of each subcomponent stretching pass was 15%, the stretching speed was 20m / min, and the cut-to-length length was 1000mm. A Ta rod with a diameter of Φ35 and a length of 1000mm was selected, and 7 hexagonal through holes with a side size of H7mm and a layer spacing of 5mm were drilled on the cross section to obtain a drilled Ta tube 4. The drilled Ta tube 4, the hexagonal subcomponent 5 and the fan-shaped subcomponent 3, the barrier layer 2 and the stabilizing matrix 1 were cleaned and treated according to Figure 1 The cross section is assembled: the hexagonal subcomponent 5 is inserted into the through hole of the drilled Ta tube 4, the fan-shaped subcomponent 3 is evenly surrounded by the outer ring of the drilled Ta tube 4 to form an annular subcomponent, the fan-shaped subcomponents 3 in the annular subcomponent are connected to each other, the fan-shaped subcomponent 3 and the hexagonal subcomponent 5 are separated by Ta, the barrier layer 2 is evenly coated on the outer ring of the annular subcomponent, and then loaded into the stable matrix 1 to obtain the final blank. After multiple drawing passes, the drawing speed is 20m / min, and the processing rate of each pass is 10%, and the Nb3Sn superconducting wire is obtained.

[0031] Performance comparison: The obtained Nb3Sn superconducting wire was heat treated and tested for performance. The heat treatment system was 575℃ / 100h+650℃ / 100h. The measured hysteresis loss was 264mJ / cm 3 (4.2K, 3T), the hysteresis loss of Nb3Sn superconducting wire prepared by the existing technology is usually 400~600 mJ / cm 3 Compared with the existing technology, the loss is significantly reduced. At the same time, the core wire area of ​​the superconducting wire prepared by this technology that reacts with Sn is increased by about 5%, and the measured critical current density is 1162A / mm 2 (12T), which is about 6% higher than the existing technology for preparing wire.

[0032] Example 2

[0033] This embodiment provides a process for preparing a Nb3Sn superconducting wire.

[0034] In this embodiment, the material of the barrier layer 2 is Ta, and the material of the stabilizing substrate 1 is oxygen-free copper.

[0035] The center of a 220-core CuNb composite rod with a diameter of Φ60mm was deep-drilled to a diameter of Φ25mm, and the cleaned Sn2Ti alloy rod was inserted into the central drilled hole of the CuNb composite tube to obtain a subcomponent blank. The subcomponent blank was subjected to multi-pass stretching and cut-to-length to obtain a hexagonal subcomponent 5 and a fan-shaped subcomponent 3, with an Nb / Sn ratio of 2.7. The processing rate of each subcomponent stretching pass was 15%, the stretching speed was 20m / min, and the cut-to-length length was 1000mm. A Ta rod with a diameter of Φ43 and a length of 1000mm was selected, and 7 hexagonal through holes with a side size of H9mm and a layer spacing of 5mm were drilled on the cross section to obtain a drilled Ta tube 4. The drilled Ta tube 4, the hexagonal subcomponent 5 and the fan-shaped subcomponent 3, the barrier layer 2 and the stabilizing matrix 1 were cleaned and processed according to Figure 1 The cross section is assembled: the hexagonal subcomponent 5 is inserted into the through hole of the drilled Ta tube 4, the fan-shaped subcomponent 3 is evenly surrounded by the outer ring of the drilled Ta tube 4 to form an annular subcomponent, the fan-shaped subcomponents 3 in the annular subcomponent are connected to each other, the fan-shaped subcomponents 3 and the hexagonal subcomponents 5 are separated by Ta, the barrier layer 2 is evenly coated on the outer ring of the annular subcomponent, and then loaded into the stable matrix 1 to obtain the final billet. After multiple drawing passes, the drawing speed is 25m / min, and the processing rate of each pass is 15%, and the Nb3Sn superconducting wire is obtained.

[0036] Performance comparison: The obtained Nb3Sn superconducting wire was heat treated and tested for performance. The heat treatment system was 575℃ / 100h+650℃ / 100h. The measured hysteresis loss was 241mJ / cm 3(4.2K, 3T), the hysteresis loss of Nb3Sn superconducting wire prepared by the existing technology is usually 400~600 mJ / cm 3 Compared with the existing technology, the loss is significantly reduced. At the same time, the core wire area of ​​the superconducting wire prepared by this technology that reacts with Sn is increased by about 6%, and the measured critical current density is 1178A / mm 2 (12T), which is about 7% higher than the existing technology for preparing wire.

[0037] Example 3

[0038] This embodiment provides a process for preparing a Nb3Sn superconducting wire.

[0039] In this embodiment, the material of the barrier layer 2 is Ta, and the material of the stabilizing substrate 1 is oxygen-free copper.

[0040] The center of a 254-core CuNb composite rod with a diameter of Φ65mm was deep-drilled to a diameter of Φ30mm, and the cleaned Sn2Ti alloy rod was inserted into the central drilled hole of the CuNb composite tube to obtain a subcomponent blank. The subcomponent blank was subjected to multi-pass stretching and cut-to-length to obtain a hexagonal subcomponent 5 and a fan-shaped subcomponent 3, with a Nb / Sn ratio of 3.0. The processing rate of each subcomponent stretching pass was 20%, the stretching speed was 30m / min, and the cut-to-length length was 1500mm. A Ta rod with a diameter of Φ45 and a length of 1000mm was selected, and 7 hexagonal through holes with a side size of H9.5mm and a layer spacing of 5mm were drilled on the cross section to obtain a drilled Ta tube 4. The drilled Ta tube 4, the hexagonal subcomponent 5 and the fan-shaped subcomponent 3, the barrier layer 2 and the stabilizing matrix 1 were cleaned and processed according to Figure 1 The cross section is assembled: the hexagonal subcomponent 5 is inserted into the through hole of the drilled Ta tube 4, the fan-shaped subcomponent 3 is evenly surrounded by the outer ring of the drilled Ta tube 4 to form an annular subcomponent, the fan-shaped subcomponents 3 in the annular subcomponent are connected to each other, the fan-shaped subcomponents 3 and the hexagonal subcomponents 5 are separated by Ta, the barrier layer 2 is evenly coated on the outer ring of the annular subcomponent, and then loaded into the stable matrix 1 to obtain the final blank. After multiple drawing passes, the drawing speed is 40m / min, and the processing rate of each pass is 25%, and the Nb3Sn superconducting wire is obtained.

[0041] Performance comparison: The obtained Nb3Sn superconducting wire was heat treated and tested for performance. The heat treatment system was 575℃ / 100h+650℃ / 100h. The measured hysteresis loss was 226mJ / cm 3 (4.2K, 3T), the hysteresis loss of Nb3Sn superconducting wire prepared by the existing technology is usually 400~600 mJ / cm 3Compared with the existing technology, the loss is significantly reduced. At the same time, the core wire area of ​​the superconducting wire prepared by this technology that reacts with Sn is increased by about 7%, and the measured critical current density is 1208A / mm 2 (12T), which is about 10% higher than the existing technology for preparing wire.

[0042] As described above, the basic principle, main features and advantages of the present invention are well described. The above embodiments and descriptions are only descriptions of the preferred implementation modes of the present invention, and the present invention is not limited by the above embodiments. Without departing from the spirit and scope of the present invention, various changes and improvements made by ordinary technicians in this field to the technical solution of the present invention should fall within the protection scope determined by the present invention.

Claims

1. An assembly structure of a niobium-tin superconducting wire, characterized in that: The assembly structure comprises: a plurality of hexagonal sub-components, a plurality of fan-shaped sub-components and a Ta tube drilled with a plurality of hexagonal holes; The hexagonal sub-component is inserted into the Ta tube drilled with a plurality of hexagonal holes, the Ta tube is surrounded by an annular sub-component composed of a plurality of the fan-shaped sub-components, and the outer ring of the annular sub-component is sequentially coated by a barrier layer and a stabilizing matrix; The hexagonal sub-component or the fan-shaped sub-component is a CuNb composite tube with a Sn2Ti alloy rod inserted in the center; The hexagonal holes in the Ta tube drilled with a plurality of hexagonal holes are separated from each other by Ta and are not connected; and the adjacent spacing between the hexagonal holes is 5-15 mm.

2. The assembly structure of the niobium-tin superconducting wire according to claim 1, characterized in that: In the hexagonal subcomponent or the fan-shaped subcomponent, the mass ratio of Nb to Sn is 1.5-4.

0.

3. The assembly structure of the niobium-tin superconducting wire according to claim 1, characterized in that: The diameter of the Ta tube drilled with a plurality of hexagonal holes is Φ20-45 mm, and the cross-sectional dimensions of the hexagonal holes are H5-H15 mm.

4. The assembly structure of the niobium-tin superconducting wire according to claim 1, characterized in that: The material of the barrier layer is Ta.

5. The assembly structure of the niobium-tin superconducting wire according to claim 1, characterized in that: The material of the stable matrix is ​​oxygen-free copper.

6. A niobium-tin superconducting wire, characterized in that: The assembled structure of the niobium-tin superconducting wire according to any one of claims 1 to 5 is obtained by multiple stretching and heat treatment.

7. The niobium-tin superconducting wire according to claim 6, characterized in that: The stretching speed of the multi-pass stretching is 5-50 m / min, and the processing rate of each pass is 5%-30%.

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